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Getting techie on Chinese drywall

That's the title of my latest HND article. We take a look at some good science—as done by the Consumer Product Safety Commission—and expose an overblown and now discredited approach.

"Overblown" and "discredited" would apply to the carelessly and perhaps cynically promoted use of x-ray fluorescence (XRF) spectroscopy as a magic bullet to discern tainted drywall. The theory was that any board with a strontium level higher than 1200 ppm (or mg/kg) would be tainted, and given the ease of using an XRF gun to make this measurement, XRF would be the way to go.

Then, the drywall test results from Lawrence Berkeley National Labs came in...

One sample, from Taian Taishan put out 185.14µg/m2/hr of hydrogen sulfide, and was rated as the second worst tested. But, its strontium content was a mere 273 mg/kg. Then there's a super-clean American board with no measurable hydrogen sulfide, with strontium at an eye-popping 2580 mg/kg.

How about one of the lowest emitting Chinese samples tested, with virtually unmeasurable sulfide emissions, and an astounding 5890 mg/kg of strontium?

Strontium APPEARED to be a marker for high sulfide, based on preliminary work, but it now seems as if the deck was stacked. Perhaps, board from particular mines with high strontium and high sulfur just happened to occur in many of the first homes tested.

I'm also inclined to believe that negative findings were suppressed. I wonder how long it will take for XRF instrument manufacturers to remove tainted drywall references from their websites—or at least acknowledge that XRF alone is not definitive?

Keep track right here:

Innov-X Systems

Oxford Instruments


Thermo Fisher Scientific

Right now, the best inspection method is still non-destructive evaluation, looking for signs of tainted drywall (corrosion to wires and HVAC components, usually accompanied by odor).

Read the complete article.



Mr. Shaw,

Again you have ferreted out the truth and facts ...

Your approach and fact checking continues to confirm, the consumer is not always being told the truth, or at best, only being told what they need to know to believe what they are being sold !!!

This article confirms, validates, and exposes the facts or should I say myths, concerning XRF Testing of "strontium" as an "ACCURATE" , "VALIDATED", or "CONFIRMED" means to identify ... Corrosive Tainted Chinese Drywall.

Clearly the science does not support ... XRF Strontium Technology Testing !!!

My firm has questioned the "XRF STRONTIUM TEST METHOD" concept from day one and want to thank you for confirming our opinion, and hope the CONSUMERS, take the time to read this article, avoiding mis-diagnosis and in-accurate laboratory test results, based on XRF STRONTIUM TESTING.

My concerns now turn to why the CPSC has not been forthcoming with this same information and educated the Consumer, Laboratories, Testing Groups, and others that have embraced, validated, confirmed, and documented numerous TAINTED CORROSIVE CHINESE DRYWALL samples, projects, residences, and structures based mainly ... if not exclusively ... on XRF STRONTIUM LEVELS.

Again, as you stated, and I agree ... NDE VISUAL ANALYSIS ... continues to be the most accurate means and method for diagnosis and validation ... structures, residences, or homes have the "CANCER" or TAINTED CORROSIVE CHINESE DRYWALL ... period !!!

Michael S. Foreman
Foreman and Associates, Inc.
Construction Consultants
Chinese Drywall Experts

Michael Shaw

Mr. Foreman--

Thank you for your comment. When the hype started on XRF, I was a bit dismayed, since it was only a marker and the relationship between strontium content and sulfide off-gassing seemed to have been created out of whole cloth.

I suspect that structures labeled as "tainted," based on XRF alone will be re-evaluated.

Tom Scotchman

I am not basing my next move on a blog posting referencing some numbers that the author typed in. This will, however, make me review my approach once more and contact the CPSC to learn what their stance is on XRF testing.

What method did the Lab use?
Is it a proven method or one that the CPSC has reviewed?


Michael Shaw


I appreciate your skepticism, but the CPSC data is quite readily available.




Would it be impolite to ask where your skepticism was when strontium content was touted as somehow magically being indicative of a still poorly understood phenomenon of sulfide content in the board?

Did it not bother you just a wee little bit that XRF seemed to show its best success in "elucidating" board that had already been determined to be tainted?

Roger Kenner


I've been using XRF as a tool for Chinese drywall and have had great success. I'm not sure who you have talked to that stated that XRF was the only tool to use but it is a tool that should be in your bag. Is the Sr levels 100% accurate? No but it is probably at least in the high 90%'s. You should always do a visual and also use the XRF for screening defective drywall. Once you find one with the XRF then you still need to send off a sample to confirm the offgasing. I have inspected hundreds of homes and without the XRF I would have passed many of them. For example, if you have a large wall without any outlets you won't see any symptoms. With the XRF I was able to see a different amount of Sr in a few of the boards in the middle of the big wall and when sent off to the lab it was defective. Without the XRF I wouldn't have found this unless I take a sample from every peice of drywall in the house and that is just not practical. Is XRF the only tool you should have? Absolutley not. But it should definitely be in your bag.

Michael Shaw


The results from the LBNL testing should definitely create some doubts in your mind.

It is also quite troubling that as far as I know, no one has ever provided a rational scientific explanation for the supposed Sr/sulfide connection. Why was the correlation so good in the 51-home study (where the correct answer was already known), but so poor when raw boards were being tested?

As I said in the main posting: I'm inclined to believe that negative findings were suppressed--before the LBNL data came in.

If--as some authorities now think--the sulfide is due to the manufacturing process (perhaps from contaminated process water), then any correlation between Sr and sulfide is fortuitous.

I've been around scientific studies for more than 30 years, and have written extensively on such matters for 15 years. This whole business reeks of "cooking the books," based on some legitimate early results.

Moreover, given the success that many inspectors have had using visual inspection only, to say nothing of the difficulties in checking every single board in the house with XRF, one wonders why it should be in your "bag" at all.

Roger Kenner


There have been hundreds of cases that inspectors have used the visual inspections in homes and have passed them, only to find out that they indeed have tainted drywall in areas that they can't visually inspect. There are a couple of major home builders as well as many realtors that have said that without XRF they would have not know the defective drywall has been in their homes. Yes some inspectors using only visual inspection only have had some sucess but those typically where the easy inspections. They are the ones that had defective drywall near an outlet or in ceilings where they can read the labels. Now most of those are done and the harder ones are popping up all over.
So if doing visual inspections can find the defective drywall 100% then why have many homes continued to have symptoms and problems after visual inspectors have cleared the house. Does this mean that the home owner should go back and Sue the inspectors that said their houses didn't have defective drywall when tested with XRF showed that it does have it? Again is XRF 100% right? No but in my experances, it has been in the 90%tile and I wouldn't inspect a home without it.

Michael Shaw


Surely you don't expect me to defend the legions of incompetent home inspectors who screwed up visual inspections.

What about real pros like Foreman, who has been right 100 percent of the time with visual methods, and is on the ASTM committee with me, that is developing standards for inspection?

BTW--I have been in the field with him, and these were not all "easy" inspections. And, yes, there are probably lots of homes that have been improperly inspected using XRF.

Think about it. There would *have* to be! The data is clear: There is NO inherent correlation between Sr and sulfide emissions. AND--quite significantly--no one has ever proffered an mechanism or explanation as to why this would be true.

I suspected that this whole business was voodoo from the start. (Some would call it "woo.")

Moreover, XRF has a long history of being misapplied, and is universally oversold by its proponents. Recent examples include a false antimony scare on toys last Christmas and absurd reports from a few years back on the "dangers" of new car smell.


That fact is that there are few applications whereby elemental analysis is useful or definitive. One that comes to mind is the magnesium content of aluminum metal stock--to ensure against sparking hazard.

I humbly suggest that you reconsider your position.


Roger and Mr. Shaw,

Appears ... based on Rogers comments, his XRF Testing is not solely the only method for his diagnosis concerning CDW.

That confirms he understands the lack of factual, confirmed, validated, Test results based solely on XRF.

Roger needs to review the CPSC and LBNL documents, a little closer, with open eyes, and an open mind. I'm convinced once that occurs, he will be sending his XRF equipment back and asking for a FULL REFUND !!!

Roger ...

ASTM committee members finally came around, and accepted my position from the start, Visual NDE, properly executed, can be 100% accurate. Simple, easy, clean, accurate, validated, and confirmed ... NDE Analysis is the best and most cost effective means and method to DIAGNOIS the presence of CDW in structures.

Future ASTM groups will tackle numerous other issues, concerning CDW, later ...

At this time ... DIAGNOISIS ... is the subject ...
You are either "INFECTED or "NOT INFECTED" ... PERIOD.

How you became infected, what type infection you have, where the infection came from, who infected you, where they got the infection, and numerous other issues are not important, at this time.

Think about CDW as a "CANCER" ...

You can spend a lot of time and money finding answers to all the above items / questions, while you die from the cancer ... or you can remove the cancer and then work on answering the questions ???

As with cancer, this is a very complicated issue, requiring a lot of research, investigation, testing, and money ... to answer all the questions.

Do you want to wait for "ALL" the answers before you react ???

Please take the time and read / review the CPSC and LBNL documents.

Michael S. Foreman
Foreman and Associates, Inc.

Roger Kenner


I have read the documents and still will not return the XRF gun. When doing inspections I think it is absolutely important to have one. You say an NDE Analysis is the most cost effective means to do a CDW inspection but I don't think that is true. In order to fully inspect a house and be 100% sure it is not defective you would have to cut out a sample from every piece of drywall in the house and have it chemically tested. Is that what you do for your inspections? If you are looking for Chinese writing, what happens now when you get some of the defective USA made drywall. Yes there are confirmed cases of US drywall now offgasing. Who is going to pay for all the holes you put in the home and the painting,etc....

With XRF you can eliminate a lot of the distructive sampling not all of it but a lot of it. Again XRF is not perfect but it is a great tool to have in your bag for testing.

I agree with you that it is like a Cancer. If you have it get rid of it as soon as you can.

Roger Kenner
SE Drywall Inspector

Michael Shaw


Let's make sure we agree on the definition of terms.

NDE="Non-destructive evaluation." This means that you can determine if the house contains tainted drywall by looking at its EFFECTS, including corrosion. As such, no drywall samples need be taken, although some inspectors will run lab tests to corroborate their findings.

The problem with XRF, as both Foreman and I have stated, is that there is NO correlation between Sr and sulfide emissions. I grant you that during initial tests, much high Sr board from China was implicated in also having high sulfide emissions, but this was just fortuitous.

There is plenty of data now out there showing Sr and sulfide levels to have absolutely no reliable relationship. To be sure, you will still be able to find some board with high Sr and high sulfide, but this is--as stated--simply fortuitous, and is not useful, by itself, as determinant of anything.

Foreman and I are currently involved with a house that is 100% guaranteed tainted drywall by virtue of the effects, YET we have run chemical lab tests on several pieces of board for both Sr and S-8 (orthorhombic sulfur) and those results have come out negative.

SO...there are only two takeaways from this

1. Sr and S-8 do not correlate with sulfide emission OR

2. We did not pull the "correct" samples, despite serious expertise in knowing which samples to pull.

However, if we pull too many more samples, we are getting close to the remediation cost, anyway!

Thus, NDE is proving to be more practical and more reliable than lab methods--unless, as you say, you want to pull every piece of board in the house,



First, as Mr. Shaw pointed out ...

NDE (Non-Destructive Examination) CDW Analysis, does not require drywall samples, or sampling just for the record. As a matter of fact ... your method of "DIAGNOSIS" with XRF and then sampling, further confirms my position.

NDE CDW Analysis is the most accurate, cost effective method, and is blind to what country the board was manufactured in and when.

NDE CDW Analysis as stated, confirms EFFECTS on building components and items with-in the structure, confirming the out-gassing effects, with simple, visual, validation and confirmation.

Yes, I agree American Board is suspect, but look at your own XRF findings, and you will see ... A lot of American Boards "TEST POSITIVE" based on XRF Guidelines, and after being "Chamber Tested" fail to out-gas levels consistent with "Corrosive" boards.

Based on CPSC and LBNL documents, your XRF markers or guidelines are flawed, in-consistent, in-accurate, un-validated, and lack scientific confirmation.

Now, back to your concerns about patching holes and painting ...

Not one of my NDE CDW Analysis (over 600), to-date, has required DE (Destructive Examination), unless the client wanted to know what brand or manufacturer for legal reasons.

Then and only then is it important to know what brand and manufacturer, to calculate percentage of "TAINTED and CORROSIVE" drywall boards, that still require "Chamber Testing" to confirm levels of out-gassing, validating specific brand and manufacturer out-gassed and specific level of out-gassing for each brand, manufacturer, batch, and date of manufacturing, found in that specific structure.

Prior to our AbissoCleanse abatement protocol and AbissoCleanse Treatment application, we recommend an EPO (Evidence Protection Order) Inspection per Judge Fallon's guidelines, that also tracks documents, confirms, and validates information required to pursue legal issues.

Again, please explain, how does XRF Testing, confirm and validate any of these issues ???

Do yourself a favor, stop performing CDW Analysis or Inspections with XRF Testing and avoid going to court when sued, and being embarrassed, humiliated, and laughed out-of-court, by a sharp attorney.

Michael S. Foreman
Foreman and Associates, Inc.
Forensic Construction Consultants
Sarasota, Florida

Michael S. Foreman

Foreman and Associates, Inc.
"Construction Consultants"
2511 Bee Ridge Rd
Sarasota, Florida 34239
Phone: 941-955-8111
Fax: 941-362-4999

Roger Kenner


So you are saying that you can do a full CDW inspection and know 100% that the house is not contaminated by doing a 100% non-destructive examanation???????
I have at least 10 homes I would love for you to inspect and show me that it is or isn't affected with CDW. If you can do this without any distructive tests then I will hire you for all of my inspections. I was in one that had no visual evidence of CDW, no discolored wires, A/C coils or anything. The customer just wanted to make sure that when he buys the house it is going to be ok. It actually was inspected by another inspector and he cleared it. When I went in with the XRF (Screening Tool) again Screening Tool I found 5 boards that were in suspect and when I sent them off for a test they indeed offgas. What would you do in this case? You keep saying that XRF is bad but if I can find CDW where others can't, how can that be bad. Is it going to always be the case? NO but it has been at least 90% accurate and I would rather do that then say a house is fine when it really isn't.
AGAIN, I don't just realy on XRF, it is a screening tool, just like your eyes are a screening tool when you look at copper in the home. Can you say 100% that due to the blackening of the copper they have CDW? NO
They could have high Sulpur in their water or in the air, so I guess we should say due to this that your eyes aren't reliable, inconsistant, in-accurate and flawed??????
I think someone needs to show you first hand some examples of why XRF is being used and if used correctly can be a great tool in your bag. Again it is a screening tool that helps but is NOT, I repeat NOT going to tell you that you 100% have CDW. Further tests need to be carried out in order to confirm. Maybe you just say someone or talked to someone about XRF that didn't know what they were talking about or that they were stretching the truth.

Roger Kenner

Michael Shaw


Foreman's contact information is posted. I suggest that you talk to him. Yes, absolutely, you can determine if a house has tainted drywall or not via NDE.

And, yes, XRF is useless, since (I think I've said this before) Sr does not reliably correlate with sulfide emissions. Any apparent correlation is merely fortuitous. The CPSC spent a lot of money to test the supposed correlation, but came up empty.

There are ways to exclude sulfur derived solely from well water.


Mr. Shaw,

Obviously, Roger Kenner was not serious about his statements ...

Never heard a word from him ???

Sure would like to show him the way ...

I think he has GOOD intentions, just misdirected ...

As the old saying goes ...

You can lead a horse to water ... but can not make him drink the water ...

Michael S. Foreman
Foreman and Associates, Inc.
Forensic Construction Consultants

Tom Scotchman

"Sure would like to show him the way ..."

What a t***. [vulgar for fecal material]--Ed.

Michael Shaw

I notice that Tom is back. Can we assume that his intelligent post here reflects the fact that he checked with the CPSC and found out that Foreman and I are right?

MEMO to anyone still using XRF for Chinese Drywall: I see many lawsuits in your future.

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